This invention relates to an illuminated speedometer display or speed indicator display.
Every automobile, and most operating machinery having the necessity of an operator governing its speed of operation, contains some means of visual depiction of the relative speed of operation of the machine in comparison to some standard. Thus, the standard automobile speedometer indicates the speed of travel of the automobile, usually in miles per hour over the road, and legal limits are established with regard to this measurement. In order to emphasize the importance of and to ease the operator's burden in determining the performance against these speed ranges of the machine, various illumination methods have been developed for illuminating the scales of such displays.
Thus, U.S. Pat. No. 3,654,452 to Frey discloses an instrument panel for motor vehicles in which a remote light source is provided. Light is conducted to the various instruments and indicators on the instrument panel by means of a glass fiber cable or fiber optic cable, which may be divided to provide patterns of illumination for the purpose of illuminating strips along an arm.
A significant number of patents relate to the illumination of instruments by the use of lights in conjunction with light pipes. In this context U.S. Pat. No. 3,216,294 to Blackwell discloses an illuminated indicating instrument in which a light pipe structure is disclosed for illuminating a plastic transparent pointer on the face of the instrument. The invention discloses the use of multiple illuminating lamps as a failure protection mode against the burnout of a single lamp. The invention also teaches that various colored lights may be used, providing different uniform colorations of light through the light pipe to the instrument.
U.S. Pat. No. 2,902,770 to Kadlec shows the construction of a light-transmitting dial pointer having a multiple part construction so that it may be illuminated at night and so that in the daytime it presents a high contrast color visibility from reflection.
U.S. Pat. No. 4,180,847 to Cresko discloses a light pipe construction in which the reflectance of light at the visible end of the pipe is highly attenuated so as to give an unambiguous light or dark (on/off) indication either at night under artificial light or in the daytime under high ambient daytime illumination.
U.S. Pat. No. 4,321,655 to Bouverand teaches the use and construction of a dashboard indicator in which essentially the entire panel substrate is constructed of a light transmissive material, in which interchangeable extensions are used to provide for the control of illumination.
U.S. Pat. No. 4,621,306 to Sell shows an illuminated instrument panel including a speed indicator in which a light guide plate is used to provide illumination to a liquid crystal display. The construct provides for a liquid crystal display including, in the depicted version, a speed indicating instrument in which color is provided. The patent teaches color coding of the light display to indicate varying conditions based upon a varying overall display color; the device is described as being suitable as an automotive instrument display.
U.S. Pat. No. 4,216,524 to Leveraus shows an alternate form of display panel in which positioning of lights driven by integral cables is used in lieu of fiber optics.
Finally, U.S. Pat. No. 3,857,361 to Gibson discloses as part of a display mechanism and a television tuner concept a mechanism which interposes a moveable mask between a light pipe source and a receiving series of fiber optic cables so that as the mask is rotated, varying displays are presented upon a flat, illuminated face showing a condition or information to the user.